The optimization of space for storing different kinds of material is the main benefit of mobile storage systems. However, using a mobile storage system implies security issues. When the need to open an aisle explicitly requires closing another aisle, it is very important to detect the presence of an object in the aisle before closing it.
Several detection systems have been developed and installed in mobile storage systems but two types of detection systems are currently in use. The first one uses motion sensors and assesses changes in ambient temperature produced by a moving subject. It is therefore not designed to detect a moving object since its temperature is the same as the ambient temperature. Also, motion sensors are not capable of detecting a stationary person. The second type of detection system utilizes an infrared source and an infrared receiver. Detection occurs when a subject or an object interferes with the reception by the receiver of the emitted infrared signal. Even if several sources and receivers are installed to cover the surface of the aisle, gaps can exist, leaving zones not covered by the detection system. Thus, there is a need for improvements in the detection of moving and stationary subjects and objects in mobile storage systems.